Art of metal coating



March 10, 1964 Original Filed July 50, 1957 E. P. SCHREYER ETAL ART OF METAL COATING 8 Sheets-Sheet l March 10, 1964 E. P. SCHREYER ETAL 3,124,477

ART OF METAL COATING 8 Sheets-Sheet 2 Original Filed July 50, 1957 l lll March 1964 E. P. SCHREYER ETAL 3,

ART OF METAL COATING Origirial Filed July so, 1957 8 Sheets-Sheet 3 INVENTOR.

Margh 10, 1964 E. P. SCHREYER ETAL 3,124,477

ART OF METAL COATING Original Filed July 50, 1957 8 Sheets-Sheet 4 INVENTOR. Eon x20 P. sc/wzyzz By #1256711 6- Wfl/rF/ELD AQMFM Arnmusvs March 10, 1964 E. P. SCHREYER ETAL 3,124,477

ART OF METAL comma Original Filed July 30, 1957' 8 Sheets-Sheet 5 F/ 6. 6 INVENTORS.

5014 4410 was 21? fixes/W11 64(49/7/74-20 March 10, 1964 E. P. SCHREYER ETAL 3,124,477

ART OF METAL COATING Original Filed July 50, 1957 8 Sheets-Sheet 6 March 10, 1964 E. P. SCHREYER ETAL 3,124,477

ART OF METAL COATING Origihal Filed July 50, 1957 a Sheets-Sheet 'r IN VEN TOR.

w wum Amm/eys March 10, 1964 E. P. SCHREYER ETAL 3,124,477

ART OF METAL COATING Original Filed July 30, 1957 8 Sheets-Sheet 8 BY QQA IQQMFM 3,124,477 ART OF METAL COATING Edward P.

Brookgfieid, Conn, assignors to Whitfield Laboratories,

lnc rRidgeiieid, Conn, a corporation of Connecticut Original application July 30, 1957, Sex. No. 675,085, new

Patent N0. 3,944,439, dated July 17, llhZ. Divided and this application Sept. 7, 1961, tier. No. 136,649 V 5 Claims. (Cl. ill-1G2} This application. is a division of copending application Serial No. 675,085, filed July 30, 1957, now US. Patent No. 3,044,439, granted July 17, 1962.

This invention relates to the art of metal coating and more particularly to a method and equipment for metal coating of valve.

As conducive to an understanding of the invention it is noted'that where valves are used, for example, in an internal combustion engine, they are subject to attack by products resulting from the combustion of fuels, particularly those containing lead compounds. As a result, the portion of the valve head exposed in the combustion chamber is subject to rapid oxidation and high temperature corrosion due to the hot combustion gases. This causes valve failure due to the corrosion of the valve seating face or the portion of the valve stem immediately adjacent the valve head.

It is known that aluminum and its alloys have the ability to form coatings having exceptional heat resistant, oxidation resistant, corrosion resistant and erosion resistantaproperties when alloyed with base metals such as iron, steel, cobalt, nickel base alloys, molybdenum, tungsten, titanium and the like having a high enough melting point to permit the application of such aluminum and its alloys.

Where to overcome the difficulties above pointed out affecting the valve, the latter is coated with a metal, such as aluminum or its alloys which, by diffusion, alloys with a base metal, control .of the thickness of the resulting alloy formed on the valve is essential. Such control of the thickness of the surface alloy layer is important because differences in the coefficients of expansion of the alloy layer and the base metal can set up stresses which result in scaling or spelling. Also, since the alloy layers are of a hard brittle nature, thicker layers are more prone to develop cracks than are thinner layers. Spalling or cracks maybe caused by vibration, impact or thermal.

shock and result in corrosion of the underlying base metal and failure of the article.

Furthermore, where the: excess aluminum remaining .over the alloy coating formed, is relatively thick, since Where,to control the thickness ofthe aluminum,

drainage in molten salt is attempted, the drainage is generally insufficient and cannot be dependably controlled. Consequently the resultant article may have excessively thick or non-uniform alloy and/or aluminum coatings which do not provide the desired protective characteristics.

In addition, the drainage operation is relatively difiicult to perform and increases the time required for the United States Paten 0 sum ei and Marshall c. Whitfield, senior lice coating cycle with resultant decrease in the rate of production.

it is accordingly among the objects of the invention to provide a relatively simple method and correspondingly simple equipment for providing metal objects such as valves and other componentsexposed to elevated temperatures and corrosion, with a corrosion resistant, heat resistant and erosion resistant protective alloy coating of aluminum or the like of predetermined thickness,

which coating will be substantially identical for all items coatedin a run, and which objects are coated relatively rapidly and are substantially devoid of excess and/ or nonuniform coating materialwhich might diffuse into the base metal to increase the thickness of the alloy coatingto an undesired amount.

According to the invention from its broadest aspect, the article has a coating of aluminum or aluminum alloy applied thereto and covering substantially the entire effective surface thereof. With the coating at a temperature sufficiently high so that it will diifuse into the base material, analloy will be formed therewith to provide the desired'protective coating. When the protective coating is of sufficient desired thickness, excess molten aluminum on the surface of the article is removed by brushing with rapidly moving Wire brushes which, in addition to removing the excess molten aluminum, also spreads the latter over the article to ensure that the entire surface thereof is uniformly coated.

According to oneembodirnent of the invention, the articles are dipped into a bath of molten aluminum or the like and after the articles have been in the bath a predetermined time, depending upon the thickness of the protective alloy coating desired, it is removed from the bath and while the surface aluminum is still molten, excess aluminum is removed by the application to the articles of rapidly moving wire brushes which also ensure uniform coating thereof.

According to another embodiment of the invention, the article is coated by means of metallizing, using spray guns, and thereafter the sprayed article is heated as by induction heating or gas heating for a sufiicient period to permit the formation of a protective alloy coating of desired thickness and thereupon while the surface aluminum is still molten, any excess aluminum is removed by the application to the article of rapidly moving wire brushes, which also ensures uniform coating thereof.

According to one feature of the invention, where the aluminum coating is applied by dipping the'article into a molten bath, the article is vibrated, to enhance bonding of the aluminum to the article and to reduce the time required for the article to be coated.

In .the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

FIG. 1 is a front elevational view of the machine,

FIG. 2. is a rear elevational view thereof,

FIG. 3 is a side elevational view taken along line 3-3 of FIG. 1,

FIG. 3A is a detail sectional view taken along line 3A-3A of FIG. 3,

FIG. 4 is a fragmentary side elevational view taken along line 4-4 of FIG. 1,

FIG. 5 is a plan view with parts broken away of the article holding members and supporting plate, 7

FIG. 6 is a detail view taken along line 6-6 of FIG. 2 showing the article holder actuating mechanism,

FIG. 7 is a transverse sectional view taken along line 77 of FIG. 2,

FIG. 8 is a view similar to FIG. 7 taken along line '8-8 of FIG. 2,

FIG. 9 is a top plan view of the motor mount and brush driving mechanism,

FIG. is a sectional view taken along line 1010 of FIG. 2, p

FIG. 11 is a diagrammatic view illustrating another embodiment of the invention, and

FIG. 12 is a view similar to FIG. 11 of still another embodiment of the invention. 7

Referring now to the drawings, as shown inFIG. 1, the equipment comprises a substantially rectangular base 11 having a substantially rectangular opening 12.

Rising from each of the sides of the base 11 is an upright standard 13, preferably a channel member, a cross piece 14 at the upper ends of the standards 13 retaining the latter in parallel relationship.

Extending through transversely aligned openings 15 in each of the standards 13 adjacent their lower ends, is a shaft 16 which rotatably mounts thereon a drum assembly 17. Each end 18 of the shaft 16 is rectangular as shown in FIG. 3 and is positioned in an elongated slot 19 in an adjustment block 21 affixed to the associated standard as by screws 22. Each of the blocks 21 has a pair of vertically aligned bores 23 in each of which is' positioned a screw 24, the head of which has a socket to receive an allen wrench for example, to rotate the associated screw. The inner ends of the screw are adapted to abut against the rectangular ends 18 of the shaft 16 so that the vertical position thereof may be adjusted.

The drum 17, FIGS. 1 and 2, comprises a pair of side plates 27, .28 illustratively octagonal as shown in FIG. 3, having transversely aligned openings 29 through which the shaft 18 extends. The plates 27, 28 are retained in spaced relationship by means of a plurality of tie rods 31, the threaded ends of which extend through the plates and are secured as by nuts 32.

The drum 17 is restrained from axial movement on shaft 16 by means of collars 33 on each side of plates 27, 28 aflixed to shaft 16 as by set screws 34.

Extending between the side plates 27, 28 are spindle plates 35. Four spindle plates are illustratively provided, each substantially rectangular and designated 35A, 35B, 35C and 35D. The spindle plates extend between pairs of the longitudinally opposed edges 36 of the plates 27, 28, being equidistantly spaced and mounted so that they may move slightly in direction parallel to the axis of shaft 16.

To permit such movement, each of the plates 35 has a pair of spaced recesses 37 (FIG. 2) in each of which one end of a pin 38 is positioned and secured to the plates 35 as by set pin 39. The pins 38 extend through aligned openings 41 in plates 27, 28 and a spring 42 at each end of the plate seated in aligned recesses 43 in plates 35 and plates 27, 28 centers the plates 35 between plates 27, 28 yet affords movement thereof to permit the associated vibrator 45, later described, freedom to vibrate the associ ated plate 35, yet isolate the vibrations to this plate from the other plates 35.

As shown in FIG. 1, the vibrator 45 which is preferably of the air operated type has its housing 46 secured by screws 47 to blocks 48 affixed to the associated plate 35 on the inner side thereof.

Each of the vibrators 45 is connected by an air line 51 which extends through an associated opening in plate 28 to a fitting 52 (FIGS. 1, 2 and 10) extending into one of the side walls 53 of a rectangular valve block or manifold 54, the latter having a central opening 55 through which the shaft 16 extends, the block 54 being secured to the outer surface of plate 28 as by screws 56.

As shown in .PIGS. 2 and 10, the valve block 54 has a central portion 58 and two side portions 59 which straddle the central portion and which retain the packing 61 in position. The end of shaft 16 adjacent plate 28 has an axial bore 62 threaded at its outer end as at 63 to receive an air line 65 (FIG. 1). Leading into the inner end of bore 62 is a transverse arcuate recess 66 of greater width at its outer end and the central portion 58 of block 4 54 has four radial bores 67 to each of which a fitting 52 is connected.

Thus, only one of the fittings 52 will be connected to the recess 66 at a time and in the illustrative embodiment, the fitting 52 associated with the plate 35 when at position b (FIG. 3) will be so connected, in order that onlythe vibrator 45 at such position will be energized.

Each of the plates 35 mounts a plurality of spindles 71, four spindles being illustratively shown. As all of the plates 35 and the associated spindles 71 are identical, only one of the spindles on plate 35D (FIG. 5) will be described in detail.

As shown in FIG. 5, each spindle comprises an outer sleeve 72 which extends through a bushing 73 press fitted in a suitable opening 74 in plate 35D. Encompassing the portion of sleeve 72 extending above plate 35D is a gear '75 which is secured to the sleeve 72 by a key 76. To restrain vertical movement of. the sleeve 72 in bushing 73, a snap ring 77 is positioned in an annular groove 78 in the sleeve on each of the opposed sides of gear 75, and a thrust washer 79 encompasses the sleeve 72 and is positioned against the undersurface of bushing 73.

Slidably mounted in each of the sleeves 72 is a draw bar 81 which has a head 82 at its outer end against which one end of a coil spring 83 abuts, the other end of the spring abutting against the end 84 of the sleeve normally to urge the draw bar outwardly.

The inner end 85 of the draw bar is internally threaded to receive the correspondingly threaded end 86 of a draw collet 87 of conventional type such as that put out by South Bend Lath Works, of South Bend, Indiana.

The collet 87 is longitudinally split as at 88 in conventional manner and the outer end thereof is beveled as at 91 to react against the correspondingly beveled inner surface of sleeve 72 so that when the draw bar 81 is moved outwardly by the action of spring 83, the collet will close to grip in conventional manner.

As previously described, four spindles 71 are mounted on each plate 35. To rotate the spindles simultaneously in the same'direction three idler gears 94, 95 and 96 are provided rotatably mounted on stud shafts 97 affixed to the plates 35, the gears 94 and 96 meshing with the two gears 75 on the left and right hand side of the plate (FIG. 1) and the gear 95 meshing with the two central gears 75. Thus, upon rotation of the gear 95 in one direction, the gears 75 driving the spindles 72 will be rotated in the opposite direction.

Means are provided to move the draw bars 81 inwardly against the tension of spring 83 to open the draw collet 87. This operation which occurs at position A (FIG. 3) is accomplished in the illustrative embodiment shown by means of a plurality of cams 101 (FIGS. 2 and 6) pinned as at 102 to shaft 16, and aligned respectively with the spindles 71. Each of the cams has a protruding portion 103 which will be aligned with the spindles 71 when they are at position A.

Associated with each of the spindles is a rocker arm 104 pivotally mounted at one end on a rocker arm rod 105 extending between the plates 27, 28. The free end of each rocker arm has a projecting finger 106 which is positioned between the head 82 of each draw bar 81 and the surface 107 of the associated cam 101 as shown in FIG. 6.

Thus, upon rotation of the drum in a counterclockwise direction to the position shown in FIG. 6 when the finger 106 of the rocker arm 104 rides over the cam surface 107, the rocker arm 104 will be moved outwardly or in a counterclockwise direction about its pivot 105 to force the draw rod 81 inwardly against the tension of spring 83. Thus, when the drum has rotated to position A (FIG. 6) for example, the projection 103 will have moved the draw rod to its maximum outward position for full opening of the draw collet 37.

Means are provided to rotate the drum 17 in steps of of the machine as shown in FIG. 1.

To this end, asillustratively shown in FIGS. 1, 2 and 3, a jack 112, illustratively air operated, is' pivotallyend a pawl 115, which has a drive finger 116 at its lower end. The edge of the pawl between the finger 116 and the upper end 117 thereof iscut out as at 118 to provide clearance for the drum drive pins 119.

As shown in FIG. 3, four of such pins are provided extending laterally outward from theplate 27 adjacent its periphery. The pins are so located that when initially engaged by the pawl finger 116, and the latter is moved downwardly bythe actuation of jack 114, the drum will be rotated 90 degrees.

Means are provided to move the pawl finger 116 into engagement with the successive drive pins 119 upon upward movement of the pawl to drive position.

To this end, a coil spring 121 is provided connected at one end to standard 13 and atits other end to jack 112 as at 122. Thus, when the pawl is raised, the spring 121 will retain the cut away portion 118 of the pawl against the upper pin 119 (FIG. 3) and when the lower end of the cut out portion has passed the upper pin 119, the spring 121 will move the jack and pawl inwardly about pivot 113 so that finger 116 will be in alignment with the upper pin 119 to react thereagainst upon energization'of the jack 112. 1

Means are provided to guide the pawl 115 upon movement thereof by jack 112. To this end, as shown in FIGS. 1, 3 and 3A, a pair of L-shaped bars 125 secured together as by bolts 126 are afilxed as by bolts 127 to the upper end of jack112. The legs 128 of the barsf126 are slightly spaced and as shown in FIGS. 3, 3A, a pin 129' 1 and 3, a bell crank 131 is pivotally mounted as at 132 on a block 133 affixed to standard 13 on theright side Interpose'd between the bell crank 131 and the block 133 and secured to the latter is a spacer block 134 which vertically aligns the bell crank with the end 135 of the pawl. The spacer block hasa stop conformation 136 against which the horizontal leg 137 of the bell crank is normally seated under the urging of a coil spring 138 connected at one end as at 139 to leg 137 and at its other end to the base ofthe machine.

Thus, when the pawl has been moved to its lowermost position as shown in FIG. 3, the end thereof will seat against the leg 137 which is the limit of the downward stroke'of the jack. ConsequentlyQthe lower pin 119 (FIG. 3) will be retained between the finger 116 of the pawl and the beveled surface 141 of the leg 142 of the bell crank properly to index the drum.

In the event the drum 17 should have moved faster than the pawl so that the lower pin 119 struck the 137 was seated against stop 136. This will rotate the each indexed position, an auxiliary locking mechanism isprovided.

This mechanism as illustratively shown in FIGS. 1 and 2, comprises a jack 151, also air operated, which is mounted on the standard 13 at the left side of the machine as shown in FIG. 1. The plunger rod 152 of the jack 151 which is vertically mounted, rides through aligned openings in guide blocks 153.. The lower end 154 of the plunger is designed to enter a notch 155 in a locking block 156, four of which are provided, atfixed to the outer surface of plate 28 aligned with each of the spindle plates 35 thereof. The notch 155 is so positioned that with each 90 degree rotation of the drum, as previously described, the notch 155will be directed upwardly in alignment with the plunger 152 which will be moved into the notch upon actuation of the jack 151.

7 Means are provided to remove excess coating material from the objects being processed. Such means in the illustrative embodiment shown are located to act upon the objects at position C, referring 'to FIG. 3.

To this end, as shown in FIGS. 2, 3,7 and 8, a pair of plates 161 are affixedrespectively to each of the standards 13 and extend vertically thereon. The plates ex tend outwardly from'standards 13 toward the rear of the machine and a vertical track 162 is mounted on each of said plates as by screws 164 at the outer vertical edge thereof. Slidably mounted in the tracks is a motor mounting plate 165 which extends transversely between the tracks 162.

Mounted on the outer surface of plate 165, FIGS. 3 and 9, is a motor 166 also preferably air driven, which has a vertical shaft 167 on which a worm 168 is mounted. The worm meshes with a worm gear 169 affixed on a shaft 171 rotatably mounted on plate 165 and centrally located thereon. The shaft 171 also mounts a-drive gear 172 with which the drive gear 95 on each of the plates 35 is adapted to be vertically aligned so that it may be driven by gear 172.

The motor shaft 167 also mounts a gear 175 which meshes with an idler gear 176, FIG. 9, that engages a gear 177 of a right angle drive 178 to rotate the shaft 179 of the latter. The shaft extends through an opening in a brush plate 181 which extends between a pair of arms 182 pivotally mounted as at 183 to a pair of parallel arms 18 i extending from motor plate 165. The portion of shaft 179 between the right angle drive 173 and the plate 181 is flexible to permit pivotal movement of arms 182 to adjust the position of said plate 181.

Mounted on the protruding end 185 of shaft 179 is a pair of wire brushes 136, adapted to rub against the article being processed. The shaft179 mounts a gear 187 which meshes with an idler gear 138 that engages a gear 189 affixed to a shaft 151 which also extends the brushes 186 and 186' against the articles.

drum backward to its proper 90 degree position and thereupon it would be locked in such position in the manner previously described.

To ensure that the drum will be dependably locked in through brush plate 131 and mounts a pair of Wire brushes 186 thereon.

The brushes 186 and 186' are designed to be held against the pairs of articles on the left and right side of the plates 35 to effect rubbing action thereagainst.

' Means are provided to reciprocate the'plate 165 to move the drive gear 172 thereof against gear 95 and to move In the illustrative embodiment shown, such means comprise a jack 192, also air operated, which is mounted at its upper end to the cross bar 14 of the frame and depends therefrom.

The jack has a plunger rod 193which is secured as by set screw 194 in a block 195 afiixed to the plate 165 as shown in FIG. 2.

In order. to reduce the size of the jack 192 required to reciprocate the plate 165 and the mechanism thereon, a counterweight 201 is provided extending transversely across the front of the equipment as shown in FIG. 1. The counterweight 261 is suspended by cables 2112 which ride around pulleys 263 depending from cross member 14, the cables being secured to brackets 204 mounted on plate 165 as shown in FIG. 3.

Means are provided to operate the various jacks in timed relation so that the drum 17 will be rotated step by step and locked at each position and also to perform the various other steps in the coating operation. As any suitable means such as a disc timer T reacting against a plurality of air switches S may be employed for this purpose, it will not be described.

Operation The equipment in the illustrative embodiment shown is positioned over a pot P of coating material such as a bath of molten aluminum with the rectangular opening 12 in the base 11 aligned with the open mouth M of the pot P (FIG. 1)'.

When the spindles 71 are at position A (FIG. 3) the cam 101 (FIG. 6) will have reacted against the rocker arms 104 and the associated draw bars 81 so that the collets 37 are open. The stem 2% of a valve V is positioned in each of the open collets in any suitable manretain the valves in the molten bath, to secure the desired thickness of the alloy coating which is determined empirically, the timer T again actuates the jack 112 to rotate the drum 17 through asecond angle of 90 degrees and during the course of the 90 degree movement, the valves V are moved out of the molten bath to position C. The drum 17 is locked in position as previously described and the timer T then actuates the jack 191 to lower the mounting plate 165 and also energizes the motor 166 to rotate its shaft 167. Rotation of shaft 167 will cause rotation of drive gear 172 as well as the brushes 186, 136. When the plate 165 has been lowered sufficiently, the gear 172 Will engagegear, 95 to rotate the spindles 71 and the valves V held thereby. At this time the brushes 186, 186 will also engage the valves and excess molten aluminum thereon will be wiped off.

After a predetermined period of time, the jack 191 is actuated to lift plate 165 to cause the gears 1'72 and 95 to disengage to stop further rotation of the spindles. The motor 156 is now de-energized and the locking jack 151 is actuated to unlock the drum. The jack 112 is then acner so that the heads of the valves are substantially aligned 114 downwardly. As a result, the finger 116 of pawl 115 will engage the topmost pin 11?, FIG. 3, to exert force thereagainst. As the end 135 of pawl 115 is no longer engaging the leg 137 of hell crank 131, the lower pin 119 (FIG. 3) and hence the drum 17 will no longer be locked and as the drum rotates, the lower pin 119 will engage the leg 142 of the released hell crank 131 to pivot thelatter. As the drum 17 rotates in the direction of the arrow (FIG. 6) the rocker arms 104 will move away from the projections 103 of the cams and the springs 83 of the spindles 71 will move the draw bars 81 and the collets 87 inwardly to lock the valve stems in position.

With further rotation of the drum, when it has moved substantially 90 degrees, the end 135 of the pawl 115 (FIG. 3) will abut against leg 137 of the bell crank 138 to lock the pin 119 in position, the drum having now rotated 90 degrees with the valves V in vertical position extending below the base plate as shown in FIG. 3 and emersed in the pot P of molten aluminum.

Thereupon, the jack 151 is actuated to move its plunger 152 into the associated notch 155 in block 156 to lock the drum in position. The jack 112 is then actuated in opposite direction to retract its plunger 114 and to move the pawl 115 upwardly so that finger 116 thereof will be positioned by spring 121 directly over the next pin 119 ready for the next cycle of operation.

At this time, referring to FIG. 10, the block 54 will have been rotated so that the bore 67 associated with the spindles carrying the valves V now immersed in the pot P will be aligned with the arcuate recess 66 so that the associated vibrator 45 will be energized to cause vibration of the associated plate 3513. As this plate is slidably I mounted on pins 38, it will vibrate readily and by reason of the slidable mount of the other plates 35, little vibration will be imparted thereto.

By reason of the vibration imparted to the valves V in the pot P of aluminum, the aluminum will adhere to the entire surface of the valve in the pot, so that the valve does not have to remain in the bath for an excessive period to accomplish such complete coating which, due to the high temperature of the bath might tend to dissolve the base metal of the valve.

While the valves are in the molten bath, the aluminum will start to alloy with the base metal of the valve to form the desired protective coating. After a predetermined period of time, depending upon the time it is desired to tuated to again rotate the drum to advance a new set of uncoated valves from position A to position B to be immersed in the pot of aluminum, and to. advance the valves in the pot of aluminum to position C for brushing as previously described.

When the coated valves are moved from position C to position D and then to position A, the collets 87 will be opened as previously described so that such coated valves may be removed and replaced by fresh valves to be coated.

The embodiments shown in FIGS. 11 and 12 are similar in many respects to the embodiment shown in FIGS. 1 to 10 except that the coating is applied by spraying and an independent source of heat is employed to raise the coating on the valves to molten condition.

Referring to FIG. 11 in which parts corresponding to those in FIGS. 1 to 10 have the same reference numerals primed, the drum 17' is indexed in steps of degrees from position A to positions B, C and D by means of a pawl which in this case reacts against the drive pins 119' by upward motion effected by the jack 112.

The valves V' are loaded at position A in the manner described with respect to the embodiment of FIGS. 1 to 10. After a predetermined period, under control of a timer (not shown), the drum 1'7 is rotated in a clockwise direction by pawl 115 to move the valves V to position B, where the spray heads 207 which are positioned in juxtaposition on the valves V will deposit a coating of aluminum on the surface thereof. After a predetermined period of time, the timer will cause the drum 17 to again be rotated 90 degrees to advance the coated valves V to station C. At this station the valves will be aligned with an induction heater 208 which will cause the temperature of the valves V and the aluminum sprayed coating thereon to be raised so that the coatings will become molten. After a predetermined period of time, sufiicient to permit an alloy coating of desired thiclsmess to be formed on the valves V, the drum 17 is again rotated through an angle of 90 degrees to position D.

Thereupon, the jack 209 is actuated causing the carriage 211 to move to the left. This carriage carries brushes 212 which are driven through an associated gear train 213 by a motor 214. The rotating brushes when they engage the valves will rub off excess aluminum thereon as desired.

After a predetermined period of time, the carriage 211 is retracted and the drum 17 again rotated 90 degrees to move the finished valves back to position A at which posi- 'tion the valves are released in the mannerpreviously described.

The embodiment shown in FIG. 12 is similar to the embodiment shown in FIG. 11 and corresponding parts have the same reference numerals.

In the embodimentof FIG. 12, the sprayed valves V are heated to a temperature suflicient to render the sprayed coatings molten and are also brushed at the same position D'. Thus, gas jets 215' react against the valves V to heat the latter and after the coatings thereon have become molten and sufficient time has elapsed to permit the formation of an alloy coating of desired thickness, the brushes 212' are moved into engagement with the valves to remove excess aluminum thereon.

With the method and equipment above described, the article may have an alloy coating or layer formed at the surface thereof of desired thickness. The thickness of the alloy layer is a factor of the temperature of the molten coating material determined either by the pot temperature, the induction heating temperature or the gas jet temperature; the time that the coating material is molten, which determines the amount that will diffuse into the base metal, and the efficiency of removal of excess material so as to prevent further diffusion in use. Since all of such variables may readily be controlled, it is apparent that once an article has had a protective layer formed thereon, by using the same factors for identical articles, they will all have substantially the same protective layer formed thereon and mass production is then relatively simple.

The article thus protected by the method and equipment herein described is not readily subject to oxidation, corrosion or erosion and hence has long life.

Although the method and equipment above disclosed has been illustratively described with respect to its application to coat valves, it is of course to be understood that it is within the scope of the invention to use such method and equipment to coat other articles such as turbine blades, valve guides and the like.

As many changes could be made in the above method and equipment, and many apparently Widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. The method of forming a protective, heat resistant, corrosion resistant and erosive resistant metal coating on a metal article which comprises the steps of applying a coating of molten metal selected from the group cons-isting of aluminum and aluminum alloys, on an individual article over the entire effective surface thereof and while the coating is still molten to permit alloying of the coating material with the metal article, brushing the effective surface of the article in manner to remove substantially all of the excess coating material on such surface, While retaining the article and the brushing means in the same relative position with respect to each other, said brushing step being continued until the coating material is in non-molten condition.

2. The method set forth in claim 1 in which the coating is applied by dipping the article in a bath of molten aluminum coating material, and after the article has been in the bath a predetermined period to permit formation of an alloy of desired thickness, the coated article is removed from the bath and subjected to the brushing op eration.

3. The method set forth in claim 1 in which the coating is applied by dipping the article in a bath of molten aluminum coating material, while subjecting the article to vibration in the bath and after the article has been in the bath a predetermined period to permit formation of an alloy of desired thickness, the coated article is removed from the bath and subjected to the brushing operation.

4. The method set forth in claim 1 in which the coating is applied by spraying upon the article, and after the article is sprayed it is heated for a predetermined period to permit formation of an alloy of desired thickness and thereafter is subjected to the brushing operation.

5. The method set forth in claim 1 in which the article being coated is rotated while being brushed and while the article and the brushing means are retained in the same relative position.

References Cited in the file of this patent UNITED STATES PATENTS 407,222 Kofiler July 16, 1889 2,167,701 Whitfield Aug. 1, 1939 2,483,424 Marines Oct. 4, 1949 2,683,436 Marantz July 13, 1954 2,881,750 Hanink Apr. 14, 1959 2,885,304 Thomson et al. May 5, 1959 2,926,103 Brick Feb. 23, 1960 2,970,065 Greene et a1 Jan. 31, 1961 3,004,864 Hanink Oct. 17, 1961 FOREIGN PATENTS 597,886 Canada May 10, 1960 678,062 Great Britain Aug. 27, 1952 

1. THE METHOD OF FORMING A PROTECTIVE, HEAT RESISTANT, CORROSION RESISTANT AND EROSIVE RESISTANT METAL COATING ON A METAL ARTICLE WHICH COMPRISES THE STEPS OF APPLYING A COATING OF MOLTEN METAL SELECTED FROM THE GROUP CONSITING OF ALUMINUM AND ALUMINUM ALLOYS, ON AN INDIVIDUAL ARTICLE OVER THE ENTIRE EFFECTIVE SURFACE THEREOF AND WHILE THE COATING IS STILL MOLTEN TO PERMIT ALLOYING OF THE COATING MATERIAL WITH THE METAL ARTICLE, BRUSHING THE EFFECTIVE SURFACE OF THE ARTICLE IN MANNER TO REMOVE SUBSTANTIALLY ALL OF THE EXCESS COATING MATERIAL ON SUCH SURFACE, WHILE RETAINING THE ARTICLE AND THE BRUSING MEANS IN THE SAME RELATIVE POSITION WITH RESPECT TO EACH OTHER, SAID BRUSH- 